Mobile snow working apparatus with adjustable height flailer

ABSTRACT

A trailer for breaking and pulverizing crusty and/or icy snow cover on a ski slope comprising a frame provided with wheels by means of which it may be transported over open roads and/or bare ground to a ski slope and skis for traversing the slope. The trailer frame has on it a motor-driven drum to which are attached a plurality of chain flails having at their distal ends breaker elements for cutting through the hard cover, and there are adjustable mounting members connecting the skis to the frame so as to enable raising and lowering the frame and hence the drum relative to the skis so that on the one hand the drum may be supported above and spaced from the snow cover to permit the flails to be turned at a rapid rate about the axis of the cylinder and to cause the breaker elements at their ends to break through the crust and on the other hand may be lowered into substantial engagement with the cover to cause the flails to become traction elements between the drum and the cover.

llnited States Patent Pease Dec. 18, 1973 MOBILE SNOW WORKING APPARATUSFOREIGN PATENTS OR APPLICATIONS WITH ADJUSTABLE HEIGHT FLAILER 108,884ll/l939 Australia 280/l2 [76] Inventor: Theodore J. Pease, 461 Faunce47,225 4/1911 Austria .1 172/45 C Rd., N th D t th, alia or ar OTHERPUBLICATIONS [22] Filed Apr 24 1972 R.P.U. Note U.S.A. case 984914 copyis provided.

[21] PP 247,142 Primary ExaminerRobert E. Pulfrey Related ApplicationData Assistant ExaminerEugene H. Eickholt [63] Continuation-impart ofSer. No. 9,267, Feb. 6, 1970, Atmmey*Rbert Gammons abandoned.

[57] ABSTRACT [52] i ga' agz i2 3;: A trailer for breaking andpulverizing crusty and/0r d 1 3 E icy snow cover on a ski slopecomprising a frame pro- [51 Hm Cl A0") 4 vided with wheels by means ofwhich it may be trans- [58] Field l6 2 92, ported over open roads and/orbare ground toa ski 172/45 240 5 7 slope and skis for traversing theslope. The trailer R 2 08 i 56/29"280/8 9 frame has on it a motor-drivendrum to which are at- E tached a plurality of chain flails having attheir distal ends breaker elements for cutting through the hard [56]References Cited cover, and there are adjustable mounting membersconnecting the skis to the frame so as to enable raising UNITED STATESPATENTS and lowering the frame and hence the drum relative to 2,967,061l/l96l Schwab 280/9 X the kis so that on the one hand the drum may beup- $503,620 3/1970 Knskfimch 280/1 ported above and spaced from thesnow cover to per- Z 32; lsobbms mit the flails to be turned at a rapidrate about the axis 3x i i l ""i' X of the cylinder and to cause thebreaker elements at l'55275O 9/1925 56/29 X their ends to break throughthe crust and on the other 3 4/194] 241/195 hand may be lowered intosubstantial engagement 3363.836 8/1966 Kucera n 56/29 X with the coverto cause the flails to become traction 2,965,320 12/1960 Pierson 241/185R elements between the drum and the cover 2597,053 5/l952 Bartch et al.t 56/29 X 2583.767 1/1952 Daignas 56/29 x 14 Clams, 11 Drawlllg Figures984 9i4 l2/l9l() Heidenheimer 280/9 J7 J7 z 2 j; ---r\ i, 17 6' J r r. lt 5 J? r- 4 L I W A 7 lk r r PATENTEIJBEE 18 can 3.779.131 9 v SHEH 2 BF4 PMENTEHnzcmusza 3379.319

sum BM 4 FIG.6

PATENTED 05c 18 ms SHEEI l 0F 4 FIG? FIGB

MOBILE SNOW WORKING APFARATUS WITH ADJUSTABLE HEIGHT FLAILER Thisapplication is a continuation-in-part of copending application Ser. No.9,267, now abandoned filed Feb. 6,1970.

BACKGROUND OF THE INVENTION US. Pat. No. 3,463,548 shows an apparatusfor breaking up and conditioning hard snow on ski slopes wherein thereis a trailer provided with skis by means of which it may be moved alonga ski trail and a motordriven drum supported thereby on which there arefixed a plurality of rigid cleats. As constructed, the drum is supportedso that its lower side in its operative position is below the surface ofthe cover and forward progress is dependent upon the cleats eating awaythe crust so as to permit the cylinder to be moved forwardly. The actionis a progressive eating away of the hard cover as the apparatusadvances. Ice breakers and snow crushers are also shown in the U.S.Pats. to Lommen 2,606,011 and Konucik 3,340,626 respectivelythe oneshowing chain-type flails attached to drums for rotation therewith tobreak up ice on highway and the other showing crusher cups secured tocutting blades to break up and throw the broken snow. Neither of thesepieces of apparatus is suitable for operating on ski slopes. It is thepurpose of this invention to provide an apparatus which, like the KellyUS. Pat. No. (3,463,548) apparatus is adapted to be drawn along a skitrail but in contrast thereto is provided with flails such as shown inLommen US. Pat. No. 2,606,011, to provide for impact breaking andpulverizing not available with the Kelly apparatus and in suchcombination as to facilitate negotiating steep and slippery slopes bothwhen travelling upwardly and when travelling downwardly without sideslip and/or jack-knifing and to further provide an apparatus which isadapted to be easily towed over highways and bare gound to the slope andthereafter to be towed over the snow cover of the ski trails forbreaking up and conditioning of the snow thereon. Other objects are toprovide for easier manipulation of the apparatus with less danger to theoperator; for better beater action and hence pulverization andconditioning of the cover; and finally for more economical use of power.

SUMMARY As herein illustrated, the trailer comprises a frame, spacedparallel skis on which the frame is supported, means on the trailerframe for connecting it to a tractor for movement of the ski-equippedtrailer on the snow cover, a drum mounted on the frame rotatable aboutan axis transverse to the skis, flails on the drum comprising elongateflexible elements attached at one end to the surface of the drum forrotation therewith, adjustable means mounting the skis to the frame suchas to enable moving the skis and frame relative to each other to raiseand lower the drum relative to the cover on which the skis rest, saiddrum normally being held by adjustment of the skis and frame relative toeach other at a level above and spaced from the cover such that only thedistal ends of the flails while travelling about the axis of the drumengage the cover as they travel between the lower side of the drum andthe surface of the cover, and means for, at times, effecting movement ofthe skis and frame to lower the drum to a position adjacent the coversuch as to engage the portions of the flails extending from the drum totheir distal ends between the lower surface of the drum and the snowcover as they travel therebetween to cause the flails to become tractionelements. There is also means for providing an air cushion between thetread surfaces of the skisand the snow cover on which they rest.

The invention will now be described in greater detail with reference tothe accompanying drawings, wherein:

FIG. l is a side elevation of one form of the trailer shown partly insection;

FIG. 2 is a plan view of the trailer shown in FIG. 1;

FIG. 3 is an enlarged end view of a beater drum;

FIG. 4 is a fragmentary section taken on the line 44 of FIG. 3;

FIG. 5 is a plan view of the drum unfolded;

FIG. 6 is an end elevation of an alternative form of trailer;

FIG. 7 is a side elevation taken from the left side of FIG. 6;

FIG. 8 is an elevation of a single wheel mount;

FIG. 9 is a diametrical section of a single beater element;

FIG. Ill) is a top plan view of FIG. 10; and

FIG. 11 is an end view of FIG. 11.

Referring to FIGS. 1 and 2, there is shown a trailer having a frame 10adapted to be alternatively supported on skis 20-20 or wheels 30--30.Each ski has fin keels 20a20a and is retractably mounted on scissor arms5 and 7 pivoted at their upper ends to the frame 10. The lower end ofarm 5 is pivoted to a fixed block 8 on the ski. The other arm 7 ispivoted to a block 9 slidable in a guideway iii. A screw 12 connected tothe midparts of the arms, provided with a hand crank 12a, is adapted byrotation to spread the arms or to draw them together thus to lower orraise the skis with respect to the frame; for example, above the levelof the wheels 30-30 to enable moving the trailer short distances on thehighway or on bare ground or to move them below the wheels so as tosupport the structure on the skis for traversing snow-covered ground andin particular the ski slopes to be conditioned. A draw bar 13 (FIG. 2)is provided for connecting the trailer to a vehicle when moving it onits wheels and a second draw bar 114 is provided for connecting it to atractor when moving it on its skis. For pulverizing and breaking upcrusty and/or icy snow there is mounted on the trailer a drum 16 ofabout 12 inches in diameter and nine feet in length, for example,journaled at each end at right angles to the skis and to the draw bar insuitable bearing members l0a--10a on the frame. Secured to thecircumference of the drum of approximately flails comprising chains 17of chain fall quality extending from openings 18, FIG. 3, in the drumand having at their distal ends beater elements 19. The chains are of alength to allow the beater elements to penetrate the snow cover of whichthe skis ride to a depth of approximately 4 inches, more or less,depending upon the adjusted positoons of the skis relative to the frame.The beater elements may comprise studded solid iron balls; however, aswill be later described, a special kind of beater element is preferred.

The drum 16 is driven by a gasoline engine shown schemically at 21 andincludes an automatic transmission 22 provided with a shift controllever 23 which provides for three forward drive speeds, 1, 2 and 3, andone reverse drive R. The shift control lever 23 as well as a throttle(not shown) are connected by Boudin cables 25 to like remote controls onthe tractor. The drum 16 and transmission 22 are connected by a belt 24and pulley 26 in a 1:1 ratio. The drum and motor are usually turned atabout 1,000 RPM constant speed as controlled by a governor 27 on thetransmission output shaft. The drum may be driven at one of threeforward speeds by shifting the control lever 23 in conventional fashion.From the exhaust to the engine a pipe 28 conducts the hot exhaust gasesto within a hood 29 partly around the drum 16 to minimize icing of thedrum, flails and related parts.

Depending from the hood and extending the length of the drum are breakerbars 3l31 (FIG. 1) against which the flails l7 fling snow and ice brokenfrom the ground cover. The hook and breaker bars tend to confine thepulverized cover in an annular zone around the drum so that it is brokenup not only by being beaten on the snow cover but also is broken upfurther by beating and tumbling within the hood. On an open slope thecrusty snow is thus pulverized for a period and then redeposited inloose, uniform condition, providing an improved ski surface as thetrailer is drawn up and down the slope.

As shown in FIGS. 3 to 5, the drum 16 has openings 18 which receive theend links of the chain flails 17 with a loop of the end links extendingwithin the drum. The openings are elongately rectangular, conforming tothe cross-wise dimension of the first link but too narrow to receive thesecond link at right angles to the first, the second link thereforetending to butt against the outside of the drum 16. As appears in FIG.5, the openings are arranged in straight rows parallel to the drum axis.Corresponding sets of chains are anchored on the drum by rods 41 whichextend lengthwise of the drum through loops of the end links of eachaligned set. At one end of the rods are crooks 42 engaged in notches 43at the end of the drum. An inner end plate 44 has clearance slots 46 forthe crook and is held by cap screws 47 on blocks 48 welded to the drum.An outer end plate 49 attached by screws 51 to the inner plate coversthe crook 42, preventing longitudinal movement of the anchor rods. Byremoving the three screws 51 in the cover 49 the rods 41 are readilyaccessible for removal and replacement of one or more of the chainflails 17.

While the chain anchoring openings 18 are aligned in equally spaced rowspreferably parallel to the drum axis, chains in adjacent rows lie indifferent planes normal to the drum axis. For example, in FIG. theopenings are shown as short vertical lines 4,6 102 and 104 on theunfolded drum 16. In this figure the reference numerals 4, 6, 102 and104 also represent the number of inches the opening so numbered isspaced from the lefthand end of the drum. Thus openings 6 lie in a planespaced 2 inches from openings 4. With the exception of the openings 4and 104 at each end of the drum, openings in adjacent rows lie indifferent planes, as with openings 6 and 102. In a given row theopenings are variably spaced from 2 inches apart to inches apart as withopenings 52 and 62. The result is that as the drum rotates, the chainsflails, which tend to strike at the same spacing as the openings, do notrepeatedly strike the same point or line of snow cover, but ratherstrike first one side and then the other of a portion of snow coverimparting lateral movement, fragmentation and pulverization of the wholesurface area of the cover in the path of the drum flails. Moreover, thestaggered spacing of the openings also forms counter-tuming spiralsaround the drum. For example, the mid-opening 4 and the lower opening 6are in one spiral turning to the right, whereas the upper opening 104and lower opening 102 are in a left-turning spiral. Most of theremaining openings are in right or left turning spirals which counteractthe tendency of either set of spirals to pulverize the snow cover in asingle direction lengthwise of the drum and leave the pulverized snowunevenly distributed in the wake of the drum.

As explained earlier, tractors and like vehicles designed for operationon unbroken snow surfaces are not safely operated at an angle along acontour line, and have traction and steering control limitations whenoperated uphill or downhill on full lines. When the substantial weightof the snow trailer is added to the tractors mass, there is a tendencytoward loss of traction going uphill and downhill and the possibility ofjackknifing the trailer-tractor rig going downhill. According to thepresent invention these problems are minimized by coordinating thesnow-pulverizing action of the trailer with the pulling of the tractor.

When the tractor is drawing the trailer uphill the shift control lever23 is set at one of the three forward speeds depending on the speed ofprogress of the tractor uphill or the degree of which the snow requiresto be pulverized. The gasoline engine 21 is connected by a belt 24 tothe drum 16 so that forward speed of the engine will rotate the drum inthe same direction. As the trailer travels up the slop the forwardrotation of the drum carries the flails around at a rather high speed sothat the beater elements at the distal ends of the chains strike thecrusty and/or icy snow cover at a very high speed. The impact is veryhigh and so will break up the most stubborn patches of icy crust withoutretarding the forward progress of the apparatus and so with a minimumconsumption of power since the drum itself does not engage the surface.If, at times, the slope becomes so steep or so slippery as to bedifficult to negotiate without side slip, the skis may be raised withrespect to the frame thus to lower the drum into substantial engagementwith the ski cover and thereby to engage the flails throughout theirentire length from their attached ends to their distal ends between thesurface of the cylinder and the cover and in this manner to providetraction for a sufficient length of time to traverse the difficult area.When this area has been negotiated, the skis may be returned to theirinitial position by rotation of the screws 12 to raise the drum from thesurface. This same traction may be taken advantage of when moving down aski slope to prevent the trailer from side slipping or jack-knifing withrespect to the tractor by adjusting the skis relative to the frame tobring the drum into substantial engagement with the snow cover andreversing the rotation of the motor by moving the shift control lever 23to the reverse position R.

Narrow downhill trails are usually cleared or worn slightly concave. Thesnow tends to be swept by skiers from the center and piled at the sides.Such side piled snow can be broken up and returned to the center of thetrail by conveyors mounted above the drum. The conveyors comprise twoconduits 36-36 enclosing flight screws 3232 or like feed means disposedparallel to the drum on both sides of a vertical plane through the drumtransversely of the trailer. The screws are connected to the drum bybelts 33-33 and cary small pulleys 34-34 which step down their speed.The screws feed snow between an inlet 37-37 to each conduit and anoutlet 38 on the lefthand side of the trailer. The inlets are located onoppositely directed tangents from the paths of the flails 17 within thehood enclosure 29 so that when snow is moved through the hood in eitherdirection of rotation of the drum there is an efficient tangential pathfrom the hood into one or the other of the conduits.

FIGS. 6 to 1 1 show an alternative form of the apparatus comprising aframe 40 (FIG. 7) on which there is mounted a drum 44, the ends of whichare supported by a through shaft 46, the latter being rotatably mountedin suitable bearings 48-48 supported by blades 68-68 welded or otherwisefastened to the frame. Spaced from and parallel to the drum there arebreaker bars 50-50, one at each side mounted longitudinally of theframe.

The frame is adapted to be supported by wheels 52-52 (FIG. 6) when thetrailer is being transported along a highway or over bare ground to itsplace of use and by skis 54-54 at the place of use for movement over thesnow cover which is to be broken up. According to this alternativestructure the wheels are removed when the trailer is being used on theslope and to permit easily mounting and removing the wheels the framehas secured to it tubular wheel mounting members 56-56 welded or boltedto the frame at right angles to the axis of the drum. Wheel supportscomprising shafts 58-58 (FIG. 8) are telescopically mounted in thetubular mounting members 56-56 and these have at their outer ends radialarms 60-60 (FIG. 8) which ex tend downwardly from the frame and have attheir lower ends wheel bearings 62-62 on which the wheels 52-52 arerotatably mounted. The shafts 58-58 are non-rotatably mounted in thetubular mounting members 56-56 so that the arms 60-60 extendperpendicularly downwardly from the frame; for example, by making thetubular members and shafts of square crosssection.

The skis 54-54 are mounted to the frame with their longitudinal axes atright angles to the axis of the drum for movement relative thereto, eachski being connected to the frame by scissor arms 62 and 64 (FIG. 7). Theupper ends of the arms 62 and 64 of each set of arms are pivotallyconnected by means of a pin 66 to the bearing block 68. The lower endsare pivotally connected to the skis by pivot pins 70 and 72. The pivotpin 70 pivotally connects the arm 62 to a block 78 fixed to the upperside of the ski. The pivot pin 72 connects the lower end of the arm 64to a slide 74 slidably mounted on a track 76 fixed to the upper side ofthe ski. The arms are adapted to be drawn together or spread apart bymeans of a screw 80 which is threaded through a block 82 fastened to thearm 62 and a block 84 fastened to the arm 64. Reversible electric motorsM are mounted to the underside of the frame and one of them is connectedto each of the screws and there are controls connected to each motoradapted to be mounted in the cab of the tractor which is used to drawthe trailer along the slope so that the operator may effect lowering andraising of the skis relative to the frame at will without having todismount from the tractor and make this adjustment by hand as disclosedin FIGS. 1 and 2.

Ordinarily the apparatus is operated with the skis lowered relative tothe frame in a position such that the ends of the flails will bite intothe snow by a few inches at most. If greater or lesser penetration isdesired the operator by extending or retracting the skis relative to theframe can change the degree of penetration.

The motor-driven arrangement for extending or retracting the skis alsohas the very great advantage that it enables the operator to quicklycorrect control movement of the trailer should it begin to side slip hentravelling upwardly or transversely along the slope or from overrunningor jack-knifing with respect to the tractor when travelling downwardlyon a slope by retracting the skis to an extent to bring the surface ofthe drum substantially into contact with the snow cover or at leastclose enough so that the chains and flails are engaged between thesurface of the drum and snow cover and so act on the one hand astraction means when the drum is rotating forwardly in the direction theapparatus is moving up the slope to aid in the upward movement or whenthe traileris moving down a slope to be reversed in a direction oppositethe direction of movement to apply braking action to such downwardmovement.

As previously related, the flails are link chains 17 connected at oneend to the drum and provided at their other ends with breaker elementswhich may be studded steel balls. preferably, however, the brakerelements as illustrated in FIGS. 9 to 11, inclusive, comprise shortsections of pipe connected to the ends of the chains 17. Pipe sectionsabout 2 inches long and l-% inches in diameter are suitable and theseare provided with axial slots 102 for receiving a loop 104 which in turnis connected to the last link in the chain 17. The link 104 is connectedso that its plane is at right angles to the plane of the last link andso arranged that as the chain travels in a circle around the axis of thedrum the axis of the pipe section will travel in a plane perpendicularto the axis of rotation so that the open ends of the pipe sectionsmoving in the direction of ro tation strike the snow cover. A hard weldmetal 108 is welded or brazed to the annular end surfaces ll 10 of thepipe sections. Preferably the pipe sections are comprised of a metalhaving a Shore hardness of approximately 80. When the drum is rotatingat a rate of approximately 1,000 RPM the pipe sections at the ends ofthe chains are travelling at the rate of about 6,000 feet per minute sothat when they strike the snow cover it can be readily understood thatthe impact is sufficient to break up the most stubborn patches of iceand reduce it to a consistency suitable for skiing purposes.

To prevent chunks of ice or stones from being driven laterally frombeneath the frame by the flails and possibly injuring persons in thevicinity or the operator, a flexible curtain 112 is fastened to theframe all the way around so as to extend from the frame down toapproximately the level of the skis in their most usual place ofoperation. This curtain may be comprised of rubber sheeting and ismerely suspended from the frame at its upper edge. A hood 114 covers thedrum.

The gasoline motor by means of which the drum is driven together withthe drum itself and flails comprises a considerable weight and soimposes a considerable load on the tractor, particularly when movinguphill. In order to relieve this load and thus to enable easily startinguphill and maintaining uphill progress without overloading the tractorengine, the skis 54 (FIG. 7) are provided with a plurality of very smallvertical air holes 112 which are in communication at their lower endswith the tread surface of the skis and at their upper ends with amanifold 114 which extends lengthwise of the top sides of the portionsof the skis containing these holes within which is maintained an airpressure of approximately 14 psi. Pressure is continuously supplied tothe manifold of each ski through a flexible conductor 116 which in turnis connected to a compressor 118 mounted on the frame and driven by themotor. The tread surfaces of the two skis is approximately 960 squareinches and so by maintaining a pressure in the order of about 4 psiwhich can be easily done with a compressor or with an ordinary blower,air may be forced through these holes to substantially reduce thefriction between the tread surfaces and the cover on which they rest.

To assist in connecting and disconnecting the trailer to the tractor bymeans of which it is moved either on its wheels or on the skis, a pairofjack cylinders 8686 are welded or otherwise fastened to the frame, asshown in FIG. 6, which contain long lead screws 88-88, to the lower endsof which are rotatably fixed flat plates 9090. The upper ends of thescrews are provided with cranks 9292 so that the plates may be loweredinto engagement with the ground to lift the frame for engagement of itsdraw bar 94 with the tractor. A draw bar 96 is provided for connectingthe trailer to a truck for road travel.

The flexible link chain structure of the flails with the pipe sectionsat their extremities not only provide ideal implements for breaking upcrushed snow and ice but also serve to reduce protruding stumps,outcroppings of ledge, low mounds of earth, grass, brush, small shrubsand the like and thus provide for conditioning and/or grooming trailsduring the summer season preparatory to the winter season.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents falling within the scope of the appended claims.

I claim:

1. A trailer for pulverizing crusty and/or icy snow cover comprising aframe, spaced parallel skis on which the frame is supported, means onthe trailer frame for connecting it to a tractor for movement of theskisupported trailer on the snow cover, a drum mounted on the framerotatable about an axis transverse to the skis, flails on the drumcomprising elongate flexible elements attached at one end to the surfaceof the drum for rotation therewith, adjustable means mounting the skisto the frame such as to enable moving the skis and frame relative toeach other to raise and lower the drum relative to the cover on whichthe skis rest, said drum normally being held by adjustment of the skisand frame relative to each other at a level above and spaced from thecover such that only the distal ends of the flails, while travelling ina circle about the axis of the drum, engage the cover as they travelbetween the lower side of the drum and the surface of the cover, saidadjustable means comprising pairs of arms, one pair for each ski, meanspivotally connecting one end of each pair of arms to the frame, meansfixed to the skis pivotally connecting the other end of one of the armsof each pair to the skis, means slidable along the skis in relation tothe means fixed thereto pivotally connecting the other ends of the otherarms of each pair of arms to the skis, screws connecting the midportionsof the arms of each pair of arms, said screws being rotatable to spreador contract the arms relative to each other to raise and lower the framewith respect to the skis, and means for at times effecting rotation ofthe screws to lower the drum to a position adjacent the cover such as toengage the portions of the flails extending from the drum to theirdistal ends between the lower surface of the drum and the cover as theytravel therebetween.

2. Apparatus according to claim 1, wherein the lastnamed means aremotors connected to the screws.

3. Apparatus according to claim 2, wherein there are means operablyconnected to said motor means for effecting control thereof from aremote source.

4. Apparatus according to claim 1, comprising a motor operably connectedto the drum so as to rotate the drum in a forward direction with respectto the movement of the trailer up a slope.

5. Apparatus according to claim 1, comprising a motor operably connectedto the drum so as to effect rotation thereof in a rearward directionwith respect to the downward movement of the trailer along the slope.

6. Apparatus according to claim 1, comprising beater elements fixed tothe distal ends of said flexible elements, each beater elementcomprising a hollow cylinder of predetermined length and diametersupported at said end of the flexible element so that the axis of thecylinder travels in a plane perpendicular to the axis of rotation.

7. Apparatus according to claim 6, wherein each cylinder has open endsbounded by annular surfaces, the radial thickness of which correspondsto the wall thickness of the cylinder, and wherein a hard metal isapplied to the annular surface at each end of the cylinder.

8. Apparatus according to claim 1, wherein the flexible elements arelink chains, and the last link of each chain is connected to the wall ofthe cylinder within axially disposed slots therein.

9. Apparatus according to claim 1, wherein there are axially alignedtubular mounting members fixed to the frame parallel to and intermediatethe skis and there are wheel supports telescopically engaged with saidtubular mounting members and wheels rotatably mounted thereon, saidwheel supporting members being removable from said tubular mountingmembers to permit removal of the wheels.

10. Apparatus according to claim 9, wherein the wheel supports compriseshafts adapted to be telescopically supported in said tubular mountingmembers, radial arms secured at one end to said shafts, and wheelbearings secured to the distal ends of the arms for mounting the wheels,and wherein said tubular members non-rotatably receive said shafts sothat the arms extend perpendicularly downwardly from the frame.

11. Apparatus according to claim 9, comprising jack screws secured tothe frame forwardly of the wheel supports for raising the frame to aposition to enable coupling its draw bar to a towing vehicle.

12. Apparatus according to claim 1, comprising means for ejecting air ata predetermined pressure from the lower surfaces of the skis to produceair cushions between the tread surfaces of the skis and the cover onwhich they rest.

13. Apparatus according to claim 12, wherein said means for ejecting airunder pressure from the tread surfaces of the skis comprise holesthrough said skis,

the lower ends of which are in communication with the tread surfacesthereof, manifolds fixed to the upper sides of the skis with which theupper ends of the holes are in communication, an air pump on the frame,and

means connecting the air pump to the manifolds for Squareinchessupplying air under pressure to said manifolds.

1. A trailer for pulverizing crusty and/or icy snow cover comprising aframe, spaced parallel skis on which the frame is supported, means onthe trailer frame for connecting it to a tractor for movement of theski-supported trailer on the snow cover, a drum mounted on the framerotatable about an axis transverse to the skis, flails on the drumcomprising elongate flexible elements attached at one end to the surfaceof the drum for rotation therewith, adjustable means mounting the skisto the frame such as to enable moving the skis and frame relative toeach other to raise and lower the drum relative to the cover on whichthe skis rest, said drum normally being held by adjustment of the skisand frame relative to each other at a level above and spaced from thecover such that only the distal ends of the flails, while travelling ina circle about the axis of the drum, engage the cover as they travelbetween the lower side of the drum and the surface of the cover, saidadjustable means comprising pairs of arms, one pair for each ski, meanspivotally connecting one end of each pair of arms to the frame, meansfixed to the skis pivotally connecting the other end of one of the armsof each pair to the skis, means slidable along the skis in relation tothe means fixed thereto pivotally connecting the other ends of the otherarms of each pair of arms to the skis, screws connecting the midportionsof the arms of each pair of arms, said screws being rotatable to spreador contract the arms relative to each other to raise and lower the framewith respect to the skis, and means for at times effecting rotation ofthe screws to lower the drum to a position adjacent the cover such as toengage the portions of the flails extending from the drum to theirdistal ends between the lower surface of the drum and the cover as theytravel therebetween.
 2. Apparatus according to claim 1, wherein thelast-named means are motors connected to the screws.
 3. Apparatusaccording to claim 2, wherein there are means operably connected to saidmotor means for effecting control thereof from a remote source. 4.Apparatus according to claim 1, comprising a motor operably connected tothe drum so as to rotate the drum in a forward direction with respect tothe movement of the trailer up a slope.
 5. Apparatus according to claim1, comprising a motor operably connected to the drum so as to effectrotation thereof in a rearward direction with respect to the downwardmovement of the trailer along the slope.
 6. Apparatus according to claim1, comprising beater elements fixed to the distal ends of said flexibleelements, each beater element comprising a hollow cylinder ofpredetermined length and diameter supported at said end of the flexibleelement so that the axis of the cylinder travels in a planeperpendicular to the axis of rotation.
 7. Apparatus according to claim6, wherein each cylinder has opEn ends bounded by annular surfaces, theradial thickness of which corresponds to the wall thickness of thecylinder, and wherein a hard metal is applied to the annular surface ateach end of the cylinder.
 8. Apparatus according to claim 1, wherein theflexible elements are link chains, and the last link of each chain isconnected to the wall of the cylinder within axially disposed slotstherein.
 9. Apparatus according to claim 1, wherein there are axiallyaligned tubular mounting members fixed to the frame parallel to andintermediate the skis and there are wheel supports telescopicallyengaged with said tubular mounting members and wheels rotatably mountedthereon, said wheel supporting members being removable from said tubularmounting members to permit removal of the wheels.
 10. Apparatusaccording to claim 9, wherein the wheel supports comprise shafts adaptedto be telescopically supported in said tubular mounting members, radialarms secured at one end to said shafts, and wheel bearings secured tothe distal ends of the arms for mounting the wheels, and wherein saidtubular members non-rotatably receive said shafts so that the armsextend perpendicularly downwardly from the frame.
 11. Apparatusaccording to claim 9, comprising jack screws secured to the frameforwardly of the wheel supports for raising the frame to a position toenable coupling its draw bar to a towing vehicle.
 12. Apparatusaccording to claim 1, comprising means for ejecting air at apredetermined pressure from the lower surfaces of the skis to produceair cushions between the tread surfaces of the skis and the cover onwhich they rest.
 13. Apparatus according to claim 12, wherein said meansfor ejecting air under pressure from the tread surfaces of the skiscomprise holes through said skis, the lower ends of which are incommunication with the tread surfaces thereof, manifolds fixed to theupper sides of the skis with which the upper ends of the holes are incommunication, an air pump on the frame, and means connecting the airpump to the manifolds for supplying air under pressure to saidmanifolds.
 14. Apparatus according to claim 13, wherein a pressure ofapproximately 4 psi is maintained in said manifold for skis having treadsurfaces of approximately 960 square inches.